Itinerant Air-Cooled

Wanna hear something stupid? I was taking the floats off to bring em' in to European Motorworks and buy new ones. As I was removing them, I noticed that when I had replaced the needles & seats that I left the old washer on and put the new one on. 2 washers on the seats. I'm just learning carbs but I figure this could cause the needle not to seal properly and cause the excess fuel to drain into the throats through the manifolds, past the rings and into the engine.

Have I found the problem?

Maybe maybe not, the double gaskets could have been leaking, but they definitely raised the float shut off level a bunch and this could have been the whole issue. Are the floats hollow? If they dont have fuel in them their fine...
Put it back together with 1 gasket and try it.